Top Stories: Self-Healing Plastic, a Virtual Universe, and Erasing Memories

Want to watch our universe evolve? You’re in luck. In the most detailed effort yet, astrophysicists and cosmologists have modeled the evolution of the universe right down to the formation of individual galaxies. The findings once again neatly confirm cosmologists' standard theory of the basic ingredients of the universe and how it evolved—a result that may disappoint researchers hoping for new puzzles to solve.

From bacteria to basketball players, all life as we know it encodes genetic information using two pairs of DNA letters. Not anymore. Now, along with the double helix’s two natural pairs, a bacterium growing in a California lab can incorporate and copy a third, artificial pair of letters. The newly expanded genetic code opens the way to a whole universe of new proteins—a potential boon to drug and materials developers.

Citing “extraordinary” circumstances, the World Health Organization (WHO) has declared the international spread of wild poliovirus a public health emergency of international concern, saying the recent export of polio from three nations to adjoining areas could threaten global efforts to eradicate the disease. Under the new recommendations, the three countries deemed to pose the greatest risk of further spread—Pakistan, Cameroon, and Syria—must now ensure that all residents and long-term visitors have proof of recent polio vaccination before leaving the country.

Do you remember your first birthday? How about what you ate for breakfast weeks ago? For most people, such events slip through the sieve of memory, never to be retrieved. Now, the first study of its kind in mice suggests that the brain may clear away that old information in the process of forming new memories.

Materials that heal themselves are going bigtime. Scientists have cooked up a chemical concoction that can patch a 9-millimeter-wide hole in a sheet of plastic, just like a human wound repairs itself. This scale of self-repair is orders of magnitude larger than ever demonstrated before, and the finding could lead to new kinds of airplanes and spacecraft that can repair themselves midflight.